// Check browser version
var isNav4 = false, isNav5 = false, isIE4 = false
var strSeperator = "/"; 
// If you are using any Java validation on the back side you will want to use the / because 
// Java date validations do not recognize the dash as a valid date separator.

var vDateType = 3; // Global value for type of date format
//                1 = mm/dd/yyyy
//                2 = yyyy/dd/mm  (Unable to do date check at this time)
//                3 = dd/mm/yyyy

var vYearType = 4; //Set to 2 or 4 for number of digits in the year for Netscape
var vYearLength = 2; // Set to 4 if you want to force the user to enter 4 digits for the year before validating.

var err = 0; // Set the error code to a default of zero


if(navigator.appName == "Netscape") 
{
   if (navigator.appVersion < "5")  
   {
      isNav4 = true;
      isNav5 = false;
	}
   else
   if (navigator.appVersion > "4") 
   {
      isNav4 = false;
      isNav5 = true;
	}
}
else  
{
   isIE4 = true;
}


function DateFormat(vDateName, vDateValue, e, dateCheck, dateType)  {

vDateType = dateType;
mDateValue = vDateValue;

// vDateName = object name
// vDateValue = value in the field being checked
// e = event
// dateCheck 
//       True  = Verify that the vDateValue is a valid date
//       False = Format values being entered into vDateValue only
// vDateType
//       1 = mm/dd/yyyy
//       2 = yyyy/mm/dd
//       3 = dd/mm/yyyy

   
   //Enter a tilde sign for the first number and you can check the variable information.
   if (vDateValue == "~")
   {
      alert("AppVersion = "+navigator.appVersion+" \nNav. 4 Version = "+isNav4+" \nNav. 5 Version = "+isNav5+" \nIE Version = "+isIE4+" \nYear Type = "+vYearType+" \nDate Type = "+vDateType+" \nSeparator = "+strSeperator);
      vDateName.value = "";
      vDateName.focus();
      return true;
   }
      
   var whichCode = (window.Event) ? e.which : e.keyCode;
 
   // Check to see if a seperator is already present.
   // bypass the date if a seperator is present and the length greater than 8
   if (vDateValue.length > 8 && isNav4)
   {
      if ((vDateValue.indexOf("-") >= 1) || (vDateValue.indexOf("/") >= 1))
         return true;
   }
   
   //Eliminate all the ASCII codes that are not valid
   var alphaCheck = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/-";
   if (alphaCheck.indexOf(vDateValue.charAt(vDateValue.length-1)) >= 1)  
   {
      if (isNav4)
      {
         vDateName.value = "";
         vDateName.focus();
         vDateName.select();
         return false;
      }
      else
      {
         vDateName.value = vDateName.value.substr(0, (vDateValue.length-1));
         return false;
      } 
   }
   if (whichCode == 8) //Ignore the Netscape value for backspace. IE has no value
      return false;
   else 
   {
      //Create numeric string values for 0123456789/
      //The codes provided include both keyboard and keypad values
      
      var strCheck = 'undefined,0,47,48,49,50,51,52,53,54,55,56,57,58,59,65,95,96,97,98,99,100,101,102,103,104,105';
      if (strCheck.indexOf(whichCode) != -1)  
      {
         if (isNav4)  
         {
            if (((vDateValue.length < 6 && dateCheck) || (vDateValue.length == 7 && dateCheck)) && (vDateValue.length >=1))
            {
               alert("Invalid Date\nPlease Re-Enter");
               vDateName.value = "";
               vDateName.focus();
               vDateName.select();
               return false;
            }
            if (vDateValue.length == 6 && dateCheck)  
            {
               var mDay = vDateName.value.substr(2,2);
               var mMonth = vDateName.value.substr(0,2);
               var mYear = vDateName.value.substr(4,4)
               
               //Turn a two digit year into a 4 digit year
               if (mYear.length == 2 && vYearType == 4) 
               {
                  var mToday = new Date();
                  
                  //If the year is greater than 30 years from now use 19, otherwise use 20
                  var checkYear = mToday.getFullYear() + 30; 
                  var mCheckYear = '20' + mYear;
                  if (mCheckYear >= checkYear)
                     mYear = '19' + mYear;
                  else
                     mYear = '20' + mYear;
               }
               var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
               
               if (!dateValid(vDateValueCheck))  
               {
                  alert("Invalid Date\nPlease Re-Enter");
                  vDateName.value = "";
                  vDateName.focus();
                  vDateName.select();
                  return false;
		         }
               vDateName.value = vDateValueCheck;
               return true;
            
            }
            else
            {
               // Reformat the date for validation and set date type to a 1
               
               
               if (vDateValue.length >= 8  && dateCheck)  
               {
                  if (vDateType == 1) // mmddyyyy
                  {
                     var mDay = vDateName.value.substr(2,2);
                     var mMonth = vDateName.value.substr(0,2);
                     var mYear = vDateName.value.substr(4,4)
                     vDateName.value = mMonth+strSeperator+mDay+strSeperator+mYear;
                  }
                  if (vDateType == 2) // yyyymmdd
                  {
                     var mYear = vDateName.value.substr(0,4)
                     var mMonth = vDateName.value.substr(4,2);
                     var mDay = vDateName.value.substr(6,2);
                     vDateName.value = mYear+strSeperator+mMonth+strSeperator+mDay;
                  }
                  if (vDateType == 3) // ddmmyyyy
                  {
                     var mMonth = vDateName.value.substr(2,2);
                     var mDay = vDateName.value.substr(0,2);
                     var mYear = vDateName.value.substr(4,4)
                     vDateName.value = mDay+strSeperator+mMonth+strSeperator+mYear;
                  }
                  
                  //Create a temporary variable for storing the DateType and change
                  //the DateType to a 1 for validation.
                  
                  var vDateTypeTemp = vDateType;
                  vDateType = 1;
                  var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
                  
                  if (!dateValid(vDateValueCheck))  
                  {
                     alert("Invalid Date\nPlease Re-Enter");
                     vDateType = vDateTypeTemp;
                     vDateName.value = "";
                     vDateName.focus();
                     vDateName.select();
                     return false;
		            }
                     vDateType = vDateTypeTemp;
                     return true;
	            }
               else
               {
                  if (((vDateValue.length < 8 && dateCheck) || (vDateValue.length == 9 && dateCheck)) && (vDateValue.length >=1))
                  {
                     alert("Invalid Date\nPlease Re-Enter");
                     vDateName.value = "";
                     vDateName.focus();
                     vDateName.select();
                     return false;
                  }
               }
            }
         }
         else  
         {
         // Non isNav Check
            if (((vDateValue.length < 8 && dateCheck) || (vDateValue.length == 9 && dateCheck)) && (vDateValue.length >=1))
            {
               alert("Invalid Date\nPlease Re-Enter");
               vDateName.value = "";
               vDateName.focus();
               return true;
            }
            
            // Reformat date to format that can be validated. mm/dd/yyyy
            
            
            if (vDateValue.length >= 8 && dateCheck)  
            {
            
               // Additional date formats can be entered here and parsed out to
               // a valid date format that the validation routine will recognize.
               
               if (vDateType == 1) // mm/dd/yyyy
               {
                  var mMonth = vDateName.value.substr(0,2);
                  var mDay = vDateName.value.substr(3,2);
                  var mYear = vDateName.value.substr(6,4)
               }
               if (vDateType == 2) // yyyy/mm/dd
               {
                  var mYear = vDateName.value.substr(0,4)
                  var mMonth = vDateName.value.substr(5,2);
                  var mDay = vDateName.value.substr(8,2);
               }
               if (vDateType == 3) // dd/mm/yyyy
               {
                  var mDay = vDateName.value.substr(0,2);
                  var mMonth = vDateName.value.substr(3,2);
                  var mYear = vDateName.value.substr(6,4)
               }
               if (vYearLength == 4)
               {
                  if (mYear.length < 4)
                  {
                     alert("Invalid Date\nPlease Re-Enter");
                     vDateName.value = "";
                     vDateName.focus();
                     return true;
                  }
               }
               
               // Create temp. variable for storing the current vDateType
               var vDateTypeTemp = vDateType;
               
               // Change vDateType to a 1 for standard date format for validation
               // Type will be changed back when validation is completed.
               vDateType = 1;
               
               // Store reformatted date to new variable for validation.
               var vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
               
               if (mYear.length == 2 && vYearType == 4 && dateCheck)  
               {
                  
                  //Turn a two digit year into a 4 digit year
                  var mToday = new Date();
                  
                  //If the year is greater than 30 years from now use 19, otherwise use 20
                  var checkYear = mToday.getFullYear() + 30; 
                  var mCheckYear = '20' + mYear;
                  if (mCheckYear >= checkYear)
                     mYear = '19' + mYear;
                  else
                     mYear = '20' + mYear;
                  vDateValueCheck = mMonth+strSeperator+mDay+strSeperator+mYear;
                  
                  // Store the new value back to the field.  This function will
                  // not work with date type of 2 since the year is entered first.
                  
                  if (vDateTypeTemp == 1) // mm/dd/yyyy
                     vDateName.value = mMonth+strSeperator+mDay+strSeperator+mYear;
                  if (vDateTypeTemp == 3) // dd/mm/yyyy
                     vDateName.value = mDay+strSeperator+mMonth+strSeperator+mYear;

               } 
               
               
               if (!dateValid(vDateValueCheck))  
               {
                  alert("Invalid Date\nPlease Re-Enter");
                  vDateType = vDateTypeTemp;
                  vDateName.value = "";
                  vDateName.focus();
                  return true;
		         }
               vDateType = vDateTypeTemp;
               return true;
            
            }
            else
            {
               
               if (vDateType == 1)
               {
                  if (vDateValue.length == 2)  
                  {
                     vDateName.value = vDateValue+strSeperator;
                  }
                  if (vDateValue.length == 5)  
                  {
                     vDateName.value = vDateValue+strSeperator;
                  }
               }
               if (vDateType == 2)
               {
                  if (vDateValue.length == 4)  
                  {
                     vDateName.value = vDateValue+strSeperator;
                  }
                  if (vDateValue.length == 7)  
                  {
                     vDateName.value = vDateValue+strSeperator;
                  }
               } 
               if (vDateType == 3)
               {
                  if (vDateValue.length == 2)  
                  {
                     vDateName.value = vDateValue+strSeperator;
                  }
                  if (vDateValue.length == 5)  
                  {
                     vDateName.value = vDateValue+strSeperator;
                  }
               }
               return true;
            }
         }
         if (vDateValue.length == 10   && dateCheck)  
         {
            if (!dateValid(vDateName))  
            {
// Un-comment the next line of code for debugging the dateValid() function error messages
//               alert(err);  
               alert("Invalid Date\nPlease Re-Enter");
               vDateName.focus();
               vDateName.select();
	         }
         }
         return false;
      }
      else  
      {
         // If the value is not in the string return the string minus the last
         // key entered.
         if (isNav4)
         {
            vDateName.value = "";
            vDateName.focus();
            vDateName.select();
            return false;
         }
         else
         {
			if (whichCode != 16){
	            vDateName.value = vDateName.value.substr(0, (vDateValue.length-1));
			}
            return false;
         }
		}
	}
}


   function dateValid(objName) {
      var strDate;
      var strDateArray;
      var strDay;
      var strMonth;
      var strYear;
      var intday;
      var intMonth;
      var intYear;
      var booFound = false;
      var datefield = objName;
      var strSeparatorArray = new Array("-"," ","/",".");
      var intElementNr;
      // var err = 0;
      var strMonthArray = new Array(12);
      strMonthArray[0] = "Jan";
      strMonthArray[1] = "Feb";
      strMonthArray[2] = "Mar";
      strMonthArray[3] = "Apr";
      strMonthArray[4] = "May";
      strMonthArray[5] = "Jun";
      strMonthArray[6] = "Jul";
      strMonthArray[7] = "Aug";
      strMonthArray[8] = "Sep";
      strMonthArray[9] = "Oct";
      strMonthArray[10] = "Nov";
      strMonthArray[11] = "Dec";
      
      //strDate = datefield.value;
      strDate = objName;
      
      if (strDate.length < 1) {
         return true;
      }
      for (intElementNr = 0; intElementNr < strSeparatorArray.length; intElementNr++) {
         if (strDate.indexOf(strSeparatorArray[intElementNr]) != -1) 
         {
            strDateArray = strDate.split(strSeparatorArray[intElementNr]);
            if (strDateArray.length != 3) 
            {
               err = 1;
               return false;
            }
            else 
            {
               strDay = strDateArray[0];
               strMonth = strDateArray[1];
               strYear = strDateArray[2];
            }
            booFound = true;
         }
      }
      if (booFound == false) {
         if (strDate.length>5) {
            strDay = strDate.substr(0, 2);
            strMonth = strDate.substr(2, 2);
            strYear = strDate.substr(4);
         }
      }
      //Adjustment for short years entered
      if (strYear.length == 2) {
         strYear = '20' + strYear;
      }
      strTemp = strDay;
      strDay = strMonth;
      strMonth = strTemp;
      intday = parseInt(strDay, 10);
      if (isNaN(intday)) {
         err = 2;
         return false;
      }
      
      intMonth = parseInt(strMonth, 10);
      if (isNaN(intMonth)) {
         for (i = 0;i<12;i++) {
            if (strMonth.toUpperCase() == strMonthArray[i].toUpperCase()) {
               intMonth = i+1;
               strMonth = strMonthArray[i];
               i = 12;
            }
         }
         if (isNaN(intMonth)) {
            err = 3;
            return false;
         }
      }
      intYear = parseInt(strYear, 10);
      if (isNaN(intYear)) {
         err = 4;
         return false;
      }
      if (intMonth>12 || intMonth<1) {
         err = 5;
         return false;
      }
      if ((intMonth == 1 || intMonth == 3 || intMonth == 5 || intMonth == 7 || intMonth == 8 || intMonth == 10 || intMonth == 12) && (intday > 31 || intday < 1)) {
         err = 6;
         return false;
      }
      if ((intMonth == 4 || intMonth == 6 || intMonth == 9 || intMonth == 11) && (intday > 30 || intday < 1)) {
         err = 7;
         return false;
      }
      if (intMonth == 2) {
         if (intday < 1) {
            err = 8;
            return false;
         }
         if (LeapYear(intYear) == true) {
            if (intday > 29) {
               err = 9;
               return false;
            }
         }
         else {
            if (intday > 28) {
               err = 10;
               return false;
            }
         }
      }
         return true;
      }

   function LeapYear(intYear) {
      if (intYear % 100 == 0) {
         if (intYear % 400 == 0) { return true; }
      }
      else {
         if ((intYear % 4) == 0) { return true; }
      }
         return false;
      }

